In a scroll compressor having low vibration and low noise characteristics, an intake chamber is provided at the outer peripheral portion, and a discharge port is provided at the central portion of a volute, and the compressed fluid flows in one direction, and a discharge valve, as used in a reciprocating type compressor or a rotary type compressor to compress the fluid is not needed, and the compression ratio is constant, and depending on operating conditions of the compressor, discharge pulsation is small, and a large discharge space is not needed, and the study for putting it into practical use in various fields has been made.
However, since compression chambers have many sealing portions, a great amount of leakage of the compressed fluid occurs, and particularly in the case of a scroll compressor of a small displacement capacity, such as a cooling medium compressor for home air-conditioning, it is necessary to extremely enhance dimensional accuracies of the volute portion in order to reduce the leakage gap of the compression portion; however, because of complicated shapes of parts and variations in dimensional accuracy of the volute portion, the cost of the scroll gas compressor is high, and variations in performance are large. Particularly, in a low-speed operating condition of the compressor, since the compression time is long, a great amount of gas leakage occurs during the compression, and this compressor has a drawback that its compression efficiency is lower than that of a reciprocating type compressor or a rotary type compressor.
Therefore, as a measure for solving problems of this kind, it is much expected to achieve the optimization of the dimensional accuracy of the volute portion, as well as the improvement of the compression efficiency, by an oil film sealing effect utilizing lubricating oil so as to prevent the gas leakage during the compression, and as disclosed in Japanese Patent Unexamined Publication No. 57-8386, it has been proposed to inject a proper amount of lubricating oil into the compression chambers during the compression to seal a gap of the compression chambers by an oil film of the lubricating oil, thereby improving the above drawback.
Particularly, in the refrigerating air-conditioning field, a scroll cooling medium compressor has been put into practical use, and compressors of a medium- to a large-size class, such as a package air conditioner and a chiller unit, in which a cooling medium volume per suction step is relatively large, have already been mass-produced.
FIG. 1 is an example of a general construction of a scroll cooling medium compressor of a medium- to a large-size 93 class in which the interior of a sealed vessel provides a high-pressure space. In the construction of this Figure, a compression portion and a discharge chamber 1031 are provided at the upper portion, and electrically-operated elements are provided at the lower portion, and an oil reservoir is provided at the bottom portion, and a discharge pipe 1042 serving as a final outlet of the compressor is disposed near the electrically-operated elements. After discharge cooling medium gas and lubricating oil are separated from each other at the discharge chamber 1031, the lubricating oil is returned via oil removal holes 1035 and 1036 to the space accommodating the electrically-operated elements, and is collected in the oil reservoir at the bottom portion, whereas the discharge cooling medium gas passes from the upper portion of the discharge chamber 1031 through another passage 1032 and the space accommodating the electrically-operated elements, and then is again discharged via the discharge pipe 1042. Also, in order to reduce the axial gap of the compression chambers, the lubricating oil at the bottom of the sealed vessel (chamber) 1013 is passed through an oil lift hole 1019 formed in a crankshaft 1008, a gap in a bearing for a frame 1009 which supports the crankshaft 1008 and fixedly holds a fixed scroll 1003, and a gap in a crankshaft portion of the crankshaft 1008 to lubricate sliding surfaces of the bearing, and then is caused to flow into a back-pressure chamber 1025 provided at the back surface of a revolving scroll 1006, and the back surface of the revolving scroll 1006 is urged by the lubricating oil, decreased to a medium pressure midway in the flow path thereof, and the high-pressure lubricating oil at the upper portion of the crankshaft portion. The back pressure urging force is so determined that it will prevent the revolving scroll 1006 from moving apart from the fixed scroll against the pressure of the compression chambers.
The lubricating oil in the back-pressure chamber 1025 flows through a back-pressure hole 1017, formed in a mirror plate 1004 of the revolving scroll 1006, into the compression chambers 1015 during the compression, and then is compressed and discharged, together with the intake cooling medium gas, while sealing the gap of the compression chambers 1015, and is discharged to the discharge chamber 1031 (Japanese Patent Unexamined Publication No. 56-165788).
However, in the above construction as shown in FIG. 1 in which the lubricating oil is supplied to the two sliding portions (the sliding portion of the upper bearing mounted on the frame 1009 supporting the crankshaft 1008 and the sliding portion of the bearing of the crank portion for revolving the revolving scroll 1006) engaged with the crankshaft 1008, and thereafter flows into the compression chambers 1015, there are many portions of flow into the compression chambers 1015, and the heated lubricating oil of high pressure and the cooling medium gas introduced into the lubricating oil flow into the compression chambers 1015 during the compression, so that there has been encountered a problem that the compression efficiency is lowered.
Further, the compression portion is provided at the upper portion, and the oil reservoir is provided at the bottom portion, and the supply of the oil to each of the bearing portions engaging the crankshaft 1008 is performed utilizing the pressure differential between the oil reservoir subjected to the discharge pressure and the compression chambers 1015 during the compression, and a centrifugal pumping action of the oil feed hole 1019 formed in the crankshaft 1008. In this construction, when the discharge pressure is not increased and the temperature of the lubricating oil is low in a low-speed operating condition as at the initial stage of the activation of the compressor, the pressure of the compression chambers 1015 during the compression is higher than the pressure of the lubricating oil in the oil reservoir, so that the pressure-differential oil supply can not be performed, and besides it is difficult to supply the lubricating oil of high viscosity by the centrifugal pumping action, and therefore it has been encountered a problem that the sliding portions engaged with the crank shaft 1008 are subjected to seizure.
Further, when the pressure of the oil reservoir at the initial stage of the activation of the compressor is low, the pressure differential oil supply from the oil reservoir at the bottom portion to the bearing portion supporting the crankshaft can not be performed as described above, and in addition the compressed cooling medium gas in the compression chambers 1015 during the compression flows reversely through the back-pressure chamber 1025 even to the gap in the bearing of the crankshaft 1008, and expels the lubricating oil residing in the very small bearing gap at the crankshaft 1008. As a result, there has been encountered a problem that the generation of the seizure of the crankshaft 1008 at the initial stage of the activation of the compressor is promoted.
Further, in the construction in which the discharge chamber 1031 having a volume necessary for separating the lubricating oil in the cooling medium gas is disposed above the compression chambers 1015, and also a motor (a rotor 1011 and a stator 1012) as well as the oil reservoir is disposed at the lower portion, the space for separating the lubricating oil from the cooling medium gas is separate from the space for accommodating the motor and for cooling the motor, and therefore there has been encountered a problem that the outer size of the compressor becomes large.
On the other hand, in order to solve the problem with the large outer size of the compressor, it has been proposed in Japanese Patent Unexamined Publication No. 57-198384, Japanese Patent Unexamined Publication No. 57-18491 and Japanese Patent Unexamined Publication No. 59-183095 and etc., to cool a motor while using a motor chamber as a space for separating discharge gas and lubricating oil from each other.
However, in any of these proposals, the discharge passage space between a discharge port, disposed adjacent to the compression chambers, and a discharge piping system is formed only by the motor chamber, or by a single discharge chamber and the motor chamber. When the final pressure of the compression chambers is extremely higher than the pressure of the discharge chamber or the pressure of the motor chamber, the compressed cooling medium gas is discharged from the compression chambers into the discharge chamber with an instantaneous expansion sound, and therefore the pulsation of the pressure of the discharge chamber (or the motor chamber) is large. As a result, there has been encountered a problem that the discharge piping system vibrates due to the high-pressure side pulsation, so that a quiet operation which is a characteristic of the scroll compressor is not achieved.
Also, when the pressure of the discharge chamber (the motor chamber) is higher than the final pressure of the compression chambers, the cooling medium gas intermittently flows reversely from the discharge chamber (the motor chamber) into the compression chambers to increase the pulsation, and therefore a similar problem has been encountered.
Further, since the pressure distribution of the compression chambers is generally determined by the intake pressure, the force (thrust force) tending to move the revolving scroll 1004 and the fixed scroll 1003 apart from each other in the axial direction depends on the intake pressure. Also, in order to flow the lubricating oil, introduced into the back-pressure chamber 1025 via the bearing sliding portions, into the compression chambers 1015, the back-pressure hole 1017 communicating between the back-pressure chamber 1025 and the compression chambers 1015 is so positioned that it opens to the compression chambers 1015 of a medium pressure somewhat lower on the average than the pressure of the back-pressure chamber 1025. Therefore, when the pressure of the discharge chamber 1031 is higher than the pressure of the compression chambers, the compressed fluid intermittently flows reversely from the discharge chamber 1031 to the compression chambers serving as the compression final-step portion. Therefore, the pressure distribution of the compression chambers 1015 is larger than that obtained with an ordinary pressure ratio, and the thrust force tending to move the revolving scroll 1004 apart from the fixed scroll 1003 becomes greater than the back pressure acting on the back surface of the revolving scroll 1004. As a result, the revolving scroll 1004 is moved apart from the fixed scroll 1003, thus inviting a problem that the compression performance is greatly lowered.
On the other hand, as measures for solving the above problems (the discharge chamber and the motor chamber are the separate spaces, so that the compressor has a large size, and the oil supply during the low-speed operation at the initial stage of the activation is difficult), there is a construction as shown in FIG. 2 in which a compression portion is provided at a lower portion of a sealed vessel 1201, and an electric motor 1203 is provided at the upper portion, and an oil reservoir 1215 is provided at the bottom portion, and a feed pipe 1217 for discharge gas is provided at the upper wall, and a bearing portion supporting a crankshaft 1204, as well as compression chambers, is dipped in the oil reservoir 1215 so as to achieve a small-size design, and also lubricating oil in the oil reservoir 1215 is supplied in a pressure-differential manner to the compression chambers 1216 via an oil feed hole 1211 formed in a boss 1205a of a frame 1205 supporting the crankshaft 1204, a gap in the bearing portion supporting the crankshaft 1204, an intermediate chamber 1208 provided between the frame 1205 and a revolving scroll 1206, and a communication hole 1211 formed in the revolving scroll 1206 (Japanese Patent Unexamined Publication No. 57-35184).
With the above construction, however, during the stop of the compressor, the lubricating oil flows into and fills in the compression chambers via the intermediate chamber 1208 and a discharge pipe 1214, and the starting torque at the time of re-activating the compressor is rendered excessive by the liquid compression, and therefore there have been encountered problems that the activation is impossible and that even if the activation is possible, the compressor is damaged.
On the other hand, as a measure for solving the above problem, there is a method as disclosed in Japanese Patent Unexamined Publication No. 61-213556 in which a reverse-rotation activation is performed at the time of the activation of a compressor; however, a check valve for preventing a reverse rotation of a revolving scroll due to a pressure differential developing immediately after stopping the compressor is provided in an intake passage, and it is difficult to discharge fluid from compression chambers at the time of the reverse rotation, and therefore there has been encountered a problem that the reverse-rotation activation can not substantially be performed. Also, as disclosed in Japanese Patent Unexamined Publication No. 57-153988, there is a device in which in order to prevent a cooling medium liquid and lubricating oil from flowing via a discharge port into compression chambers to fill in them during the stop of the compressor, a check valve is provided at the discharge port; however, when the intake pressure is lower than a set pressure, or when the discharge pressure is higher than a set pressure, the discharge fluid intermittently flows into the compression chambers during the operation of the compressor, and at this time the check valve is opened and closed in response thereto, so that the check valve generates impingement sounds, and therefore there has been encountered a problem that low noise characteristics of the scroll compressor are adversely affected.
Further, with respect to the oil supply to the bearing sliding portions engaged with the crankshaft 1204, although the pressure differential oil supply to the bearing portion between the oil feed hole 1212 and the intermediate chamber 1208 is sufficient, the other bearing sliding portions (the bearing portion above the oil feed hole 1212 and the bearing portion between the crank portion of the crankshaft 1204 and the revolving scroll 1206) are only dipped in the lubricating oil, and do not receive a positive circulation of the lubricating oil, and therefore there has been encountered a problem that the crankshaft is subjected to seizure.
Further, the pressure of the intermediate chamber 1208 for urging the revolving scroll 1206 toward the fixed scroll 1207 is formed only by the pressure intermediate the intake pressure and the discharge pressure, and as described later, when the intake pressure becomes lower than the set pressure, or when the discharge pressure becomes higher than the set pressure, the force for urging the revolving scroll 1206 toward the fixed scroll 1207 becomes insufficient, and the axial gap of the compression chambers becomes larger, and as a result the leakage of compressed gas is increased, and therefore there has been encountered problems that the compression efficiency is greatly lowered and that because of an abnormal temperature rise in the compression portion, the sliding portions are subjected to seizure.
On the other hand, as shown in FIGS. 3 and 4, as a method of solving the above problem (when the compression ratio is higher than the set value, the revolving scroll moves apart from the fixed scroll, so that the compression performance is lowered), there is a construction in which a differential pressure control mechanism is provided at a communication hole 1316 which communicates between a back-pressure chamber 1315, provided between a back surface of a revolving scroll 1301 having a communication hole 1314 open to a sealed space (compression chamber) 1308, and a frame 1303, and a discharge chamber 1310, and this differential pressure control mechanism performs the function of a check valve which only allows gas to flow from the discharge chamber 1310 to the back-pressure chamber 1315, and causes the pressure of the back-pressure chamber 1315 to follow the pressure of the discharge chamber 1310 so as to overcome the insufficiency of the back-pressure acting on the revolving scroll 1301 (Japanese Patent Unexamined Publication No. 58-160580).
With the above construction, however, when the amount of by-pass gas flowing from a motor chamber into the back-pressure chamber 1315 via the differential pressure control mechanism portion is large, the pressure differential supply of oil from an oil reservoir at the bottom portion to bearing portions supporting a crankshaft is insufficient, and therefore there has been encountered a problem that the bearings are damaged.
Further, when a continuous liquid compression occurs in the compression chambers 1308, the high-pressure fluid flows into the back-pressure chamber 1315 via the communication hole 1314, so that the pressure of the back-pressure chamber 1315 may become higher than the discharge pressure. As a result, the pressure differential supply of the oil from the oil reservoir at the bottom portion to the bearing portions supporting the crankshaft can not be performed, and therefore there has been encountered a problem that the crankshaft is subjected to seizure.
It is also considered that the back-pressure area of the oil chamber, which is provided at the crankshaft 1008 in FIG. 1 or at the crank head of the crankshaft in FIG. 2 and is subjected to the discharge pressure, is increased so as to increase the back-pressure urging force due to the discharge pressure, thereby solving the problem concerning the insufficiency of the back-pressure urging force occurring when the compression ratio is high, without using the thrust seal as described above. However, as described in Japanese Patent Publication No. 62-49474, in order to reduce the thrust force acting on the crankshaft by forming the opposite end portions of the crankshaft into the same diameter, the crankshaft need to be increased in diameter, which invites an input loss due to an increased frictional torque of the bearing portions and a large-size outer configuration of the compressor, and therefore it has been difficult to achieve the above proposal to solve the problem.
In view of the problems of the prior art, an object of a first invention of the present application is to perform a sufficient oil supply to bearing portions while ensuring an optimum amount of supply of oil to compression chambers so as to seal a gap of the compression chambers by an oil film.
An object of a second invention is to decrease the amount of supply of oil to the compression chambers in accordance with the increase of the operation speed of the compressor, thereby improving the compression efficiency.
An object of a third invention is to reduce wear of a rotation prevention member and a sliding surface gap of the rotation prevention member by forcible feed of oil to the rotation prevention member, thereby preventing the generation of noises due to the movement of the rotation prevention member.
An object of a fourth invention is to always keep constant the relative angle between a revolving scroll and a fixed scroll so as to keep the gap of the compression chambers to a very small level, thereby maintaining a good compression efficiency.
An object of a fifth invention is to reduce the leakage of lubricating oil from a back-pressure chamber of the revolving scroll into an intake chamber, thereby enhancing an intake efficiency of the compression chambers.
An object of a sixth invention is to enhance the durability of a movable seal member which separates the bearing portion, provided at the high-pressure side and related to a drive shaft, from the back-pressure chamber of the revolving scroll.
An object of a seventh invention is to provide an oil feed pump passage which can simultaneously supply oil to two bearings related to the drive shaft of a large load, thereby enhancing the durability.
An object of an eighth invention is to provide a space-saving oil feed pump device which can supply oil to the bearing portion related to the drive shaft simultaneously with the activation of the compressor.
An object of a ninth invention is to provide a space-saving oil feed pump which has a low speed of sliding between the drive side and the driven side, and is excellent in durability.
An object of a tenth invention is to provide an oil feed passage which can supply oil to the back-pressure chamber of the revolving scroll simultaneously with the activation of the compressor.
An object of an eleventh invention is to provide a bearing oil feed pump which has a small input loss even at the time of a high-speed operation.
An object of a twelfth invention is to provide a capacity-type pump which can supply oil only when the operating speed of the compressor is above a predetermined value, whereby the supply of a liquid cooling medium to the sliding portion at the initial stage of the activation of the compressor in a cooled condition is prevented, thereby enhancing the durability of the sliding portion.
An object of a thirteenth invention is to stabilize the pressure of the back-pressure chamber by an oil feed passage construction which supplies oil to the back-pressure chamber of the revolving scroll without causing the flow of gas thereinto.
An object of a fourteenth invention is to provide an oil feed passage which can effectively lubricate the sliding surface in the process of the flow of the lubricating oil from the back-pressure chamber of the revolving scroll into the compression chambers.
In order to achieve the above objects, in a scroll compressor of the first invention, there is provided a bearing oil feed passage in which by an oil feed pump operated by the rotation of a drive shaft, lubricating oil in an oil reservoir subjected to a discharge pressure is supplied to a main bearing, supporting the drive shaft and disposed close to a revolving scroll, and a revolving bearing slidably connecting the drive shaft and the revolving scroll together, and thereafter is returned again to the oil reservoir, and there is provided an oil injection passage having a throttle passage which supplies part of the lubricating oil, supplied to at least one of the bearings, sequentially via a back-pressure chamber of the revolving scroll and compression chambers.
In the second invention, there is provided an oil feed passage which passes sequentially via an oil reservoir, communicated with a discharge chamber, a back-pressure chamber of a revolving scroll and leads to compression chambers, and there is provided means for intermittently opening and closing the flow inlet of the back-pressure chamber and the communication passage between the back-pressure chamber and the compression chambers in response to the revolution of the revolving scroll.
In the third invention, there is provided an oil feed passage passing sequentially via an oil reservoir, a back-pressure chamber and compression chambers, and means for intermittently opening and closing the flow inlet of the back-pressure chamber is based on a reciprocal movement of a sliding surface of a self-rotation prevention member.
In the fourth invention, there is provided an oil feed passage passing sequentially via an oil reservoir, a back-pressure chamber and compression chambers, and means for intermittently opening and closing the flow inlet of the back-pressure chamber is based on a reciprocal movement of a key portion of a self-rotation prevention member in sliding contact with a body frame.
In the fifth invention, there is provided an oil feed passage passing sequentially via an oil reservoir subjected to a discharge pressure, a back-pressure chamber of a revolving scroll, an outer peripheral space around a wrap support disk supporting a volute-like wrap of the revolving scroll, and compression chambers, and a throttle passage between the back-pressure chamber and the outer peripheral space is intermittently communicated in accordance with the revolution of the wrap support disk.
In the sixth invention, means for intermittently opening and closing the flow inlet of a back-pressure chamber is provided between a body frame, supporting a drive shaft, and a revolving scroll so as to sealingly separate a bearing portion, which is at the high-pressure side and is related to the drive shaft, from the back-pressure chamber of the revolving scroll, and this means is based on a revolution of a sliding sealing surface of an annular seal member movably mounted on the revolving scroll.
In the seventh invention, an oil suction passage, which is communicated between a revolving bearing slidably connecting a drive shaft and a revolving scroll together, and a main bearing supporting that side of a drive shaft close to the revolving scroll, is communicated with an oil reservoir subjected to a discharge pressure, and spiral oil grooves having a viscosity pumping action are formed respectively in the sliding surfaces of the two bearings, and the oil suction passage is communicated with the suction side of the spiral oil grooves.
In the eight invention, a trochoid pump, which comprises an inner rotor connected to a drive shaft and an outer rotor received in a revolving scroll, is provided at that side of a revolving bearing close to compressing chambers which revolving bearing slidably connects the drive shaft and the revolving scroll together, and there is provided an oil feed passage in which an oil reservoir subjected to a discharge pressure is at its most upstream side, the revolving bearing is at its upstream side, and the bearing sliding portion supporting the drive shaft is at its downstream side.
In the ninth invention, there is provided an oil feed pump device in which an outer peripheral portion of a sliding connection portion between a drive shaft and a revolving scroll is slidably contacted with an inner surface of an annular piston disposed outside thereof, and the piston is swingingly moved in response to the revolution of the revolving scroll so as to perform a pumping action, and this pump device is provided between a main bearing, which supports a drive shaft and is disposed close to the revolving scroll, and the sliding connection portion, and the oil feed pump device is provided halfway in an oil feed passage communicating between an oil reservoir subjected to a discharge pressure and the bearing sliding portion related to the drive shaft.
In the tenth invention, a capacity-type oil feed pump device, which is operated in response to rotation of a drive shaft, is provided between a main bearing, which supports the drive shaft and is disposed close to a revolving scroll, and the revolving scroll, and there is provided an oil feed passage passing sequentially via an oil reservoir subjected to a discharge pressure, a bearing sliding portion related to the drive shaft, a back-pressure chamber of the revolving scroll and compression chambers, and the capacity-type oil feed pump device is provided halfway in the oil feed passage between the oil reservoir and the back-pressure chamber.
In the eleventh invention, there is provided an oil feed pump device in which an outer peripheral portion of a sliding connection portion between a drive shaft and a revolving scroll is slidably contacted with an inner surface of an annular piston disposed outside thereof, and part of the outer periphery of the piston is movably engaged with a stationary member, and the piston is swingingly moved in response to the revolution of the revolving scroll so as to perform a pumping action, and this pump device is provided between a main bearing, which supports a drive shaft and is disposed close to the revolving scroll, and the sliding connection portion, and the oil feed pump device is provided halfway in an oil feed passage communicating between an oil reservoir subjected to a discharge pressure and the bearing sliding portion related to the drive shaft.
In the twelfth invention, a slide vane-type oil feed pump device, which comprises a rotor rotatable coaxially with a drive shaft, and a vane movable back and forth in a groove in the rotor so as to divide a pump chamber, is provided between a main bearing, which supports the drive shaft and is disposed close to a revolving scroll, and the revolving scroll, and the slide vane-type oil feed pump device is provided halfway in an oil feed passage communicating between an oil reservoir subjected to a discharge pressure and the bearing sliding portion related to the drive shaft, and the back-pressure urging force of the vane depends on the centrifugal force based on the weight of the vane.
In the thirteenth invention, there is provided a pressure differential oil feed passage passing sequentially via an oil reservoir subjected to a discharge pressure, an oil reservoir provided between two bearings supporting a drive shaft, a back-pressure chamber of a revolving scroll, and compression chambers, and a throttle passage is provided between the back-pressure chamber and the oil reservoir.
In the fourteenth invention, there is provided a pressure differential oil feed passage passing sequentially via an oil reservoir subjected to a discharge pressure, a back-pressure chamber of a revolving scroll, an outer peripheral space where the revolving scroll and a fixed scroll is slidably contacted with each other outside an intake chamber, a communication passage formed in the fixed scroll and opening to a sliding surface of a mirror plate, and compression chambers, and the open portion of the oil passage, communicating between the back-pressure chamber and the outer peripheral space, and the open portion of the communication passage formed in the mirror plate are disposed in opposite relation to each other with respect to the center of the revolving scroll.